The present invention relates to a vehicle tire having an improved tread portion in which the rigidity difference between the tread pattern design units having different pitch lengths is decreased to improve the tire uniformity, steering stability and the like.
In general, a pneumatic tire is provided in the tread with a tread pattern formed by repeating a design unit along the circumference of the tire, and most of the tread patterns employ variable pitches in arranging the design unit.
If the circumferential widths of grooves in every design unit are varied in proportion to the pitches, the sea/land ratio or the ratio of the grooved area to the remaining area is evened through all the design units, and as a result the ground pressure distribution of the tire becomes uniform. Thus this does not seem to involve problems. In fact, however, it is difficult to improve the tire uniformity, running noise, steering stability and the like. Therefore, the present inventor studied and found that the pattern rigidity of the design unit is not always evened although the ground pressure distribution is evened.
It is therefore an object of the present invention to provide a pneumatic tire in which the design units are evened in the pattern rigidity to improve the tire uniformity, steering stability, running noise and the like without worsening the ground pressure distribution.